Julian Regel wrote:
>It is actually not that easy.
>
>Compare a cost of 2x x4540 with 1TB disks to equivalent solution on LTO.
>
>Each x4540 could be configured as: 4x 11 disks in raidz-2 + 2x hot spare
>+ 2x OS disks.
>The four raidz2 group form a single pool. This would provide well over
>30TB of logical storage per each box.
>
>Now you rsync all the data from your clients to a dedicated filesystem
>per client, then create a snapshot.
>All snapshots are replicated to a 2nd x4540 so even if you would loose
>entire box/data for some reason you would still have a spare copy.
>
>Now compare it to a cost of a library, lto drives, tapes, software +
>licenses, support costs, ...
>
>See more details at
>http://milek.blogspot.com/2009/12/my-presentation-at-losug.html
I've just read your presentation Robert. Interesting stuff.
I've also just done a pen and paper exercise to see how much 30TB of
tape would cost as a comparison to your disk based solution.
Using list prices from Sun's website (and who pays list..?), an SL48
with 2 x LTO3 drives would cost £14000. I couldn't see a price on an
LTO4 equipped SL48 despite the Sun website saying it's a supported
option. Each LTO3 has a native capacity of 300GB and the SL48 can hold
up to 48 tapes in the library (14.4TB native per library). To match
the 30TB in your solution, we'd need two libraries totalling £28000.
You would also need 100 LTO3 tapes to provide 30TB of native storage.
I recently bought a pack of 20 tapes for £340, so five packs would be
£1700.
So you could provision a tape backup for just under £30000 (~$49000).
In comparison, the cost of one X4540 with ~ 36TB usable storage is UK
list price £30900. I've not factored in backup software since you
could use an open source solution such as Amanda or Bacula.
A more apples to apples comparison would be to compare the storage
only. Both removable drive and tape options require a server with FC or
SCSI ports, so that can be excluded from the comparison.
So for 30TB, assuming 2TB drives @ ~£100 with a pool built of 6 drive
raidz vdevs 18 drives would be required plus 2 16 drive shelves. So
each backup set would cost about £1800. So there's not a great deal of
difference. With drives you also get the added benefit of keeping all
your incrementals (as snapshots) on the archive set.
HDD price per GB will continue to drop faster than tape, so it will be
interesting to do the same comparison in 12 months.
--
Ian.
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